1.Field of the Invention
The present invention relates generally to a method of an apparatus for forming coil springs and, more particularly, to a method of and an apparatus for forming coiled portions, arcuated portions of hooks, or bent portions of various coils by applying a forming tool to a wire fed from a quill.
2. Description of the Prior Art
It is known that such a spring, for example, a torsion coil spring is produced in the following way. A plurality of forming tools are radially disposed around a wire fed from a quill, and the forming tools are sequentially moved toward and away from the wire in one-by-one fashion, whereby the individual forming tools are separately operated to form various portions of a spring such as an arcuated portion of a first hook, a bent portion between the first hook and a coiled portion and a body portion as well as a leading portion and an arcuated portion of a second hook.
However, since many such forming tools are constituted as separate units each including various components such as a tool holder and a drive mechanism, the cost of production is increased. Further, since a space for these forming units is limited on the front side of a tool mounting frame, a limited number of forming tools can only be mounted. As a result, it becomes difficult to form a spring having a complicated configuration, and the mechanism becomes complicated as a whole.
As disclosed in, for example, Japanese Examined Publication Pat. No. 56-12379, a conventional type of spring forming apparatus is typically arranged such that forming and cutting tools are directly driven by means of a single large gear, the operating timing of each of the forming and cutting tools being controlled by the rotation of the single large gear. However, drive cams associated with the forming tool require upward or downward slopes while they are rotating from working position to non-working position, or vice versa, and an angle at which each cam is driven depends upon the kind of spring to be formed. Therefore, if the number of forming tools excessively increases or the kind of spring to be formed is changed, it will become impossible to arrange the driving angles for all the cams during the rotation of the single large drive gear, and hence no proper timings can be set. For these reasons, since the number of tools used and angles required for forming are limited, the pattern of movement of a forming slide which holds a forming tool is limited, with the result that the movement pattern cannot be freely modified.
In addition, it is difficult to adjust the timing of each cam that is required to move forming and and cutting tools at proper timings, and therefore time-consuming and inefficient operations of correcting and gauging the configurations of the cams have been required for assembly thereof.